The production of beta-lactamase (penicillinase) enzymes by bacteria is still an important factor in bacterial resistance to penicillin therapy and seems to be coming more so with the movement by conjugation of plasmids coding for beta-lactamases into previously non-producer species e.g. N. gonorrhoeae. Despite considerable effort no general inhibitor of these enzymes is yet available. Progress towards the development of such and inhibitor is likely to come at this stage only from an understanding of the mechanism of action of these enzymes which at the moment is almost completely lacking. The objective of the proposed research is to examine in detail the mechanism of action of a recently discovered, potent, active site directed, irreversible beta-lactamase inhibitor, 6-beta-bromopenicillanic acid, and a variety of beta-lactamases, should lead to a better idea of the mechanism of the beta-lactamase action of these enzymes and to a broader view at an active-site level of the variation of these enzymes among bacterial species. It is hoped that the work might also lead to a clinically useful general inhibitor. Finally it is proposed that an investigation of the interaction of these inhibitors with bacterial cell wall components could lead to results bearing on the questions of beta-lactamase evolution, the mechanism of antibiotic action of penicillins and the relationship between these.